CVE-2026-77696

3.7 LOW 0.4% exploit odds Fix listed Other

What it is

Issue summary: SM2 signature generation uses non-constant-time arithmetic on secret values, forming a timing side-channel. Impact summary: An attacker able to measure SM2 signing times may learn information about the per-signature secret nonce, which over many signatures can, via a lattice / Hidden Number Problem attack, lead to recovery of the private key. CWE: CWE-208: Observable Timing Discrepancy Description: SM2 signature generation computes the signature value using variable-time BIGNUM operations on the secret nonce and the private key, so the time taken to produce an SM2 signature depends on these secret values, forming a timing side-channel. Applications performing SM2 signature generation are affected on all platforms. FIPS Impact: no SM2 is not a FIPS algorithm.

At a glance

Exploitability: Can be exploited over the network without logging in. Limited direct impact.
Exploit odds: 0.4% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-09-29 16:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-10-08 01:20 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.4% in the next 30 days (EPSS).
Severity: 3.7 LOW (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-09-29 16:17 UTC
Last modified: 2026-10-08 01:20 UTC
Exploit probability: 0.4% · EPSS, next 30 days
Weakness: CWE-208
Record status: Analyzed

Affected

OpenSSL < 1.1.1zj
OpenSSL < 3.0.23
OpenSSL < 3.4.8
OpenSSL < 3.5.9
OpenSSL < 3.6.5
OpenSSL < 4.0.3

Attack profile CVSS 3.1 · 3.7

Attack vector: Network
Complexity: High
Privileges needed: None
User interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: None
Availability: None

Raw vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

Is it in your code?

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Fix and advisories

References

NVD record · CVE.org record